In the process of drilling an oil well, a well cellar is dug into the ground through which the well bore is drilled. The well cellar serves to contain drilling equipment and to collect well drilling fluid (drilling mud) during drilling operations. A pump, sometimes referred to as a trash pump, is positioned within the cellar and is operated to continually pump fluid from well cellar to separate tanks Failure of the trash pump during drilling operations often results in the drilling fluid overflowing cellar and spilling out on to the surrounding ground.
Cleanup of the fluid spill is costly and may require reporting to regulatory bodies if the spill exceeds a certain volume of fluid. Accordingly, several procedures haven been attempted to prevent a spill. One procedure includes positioning a member of the drilling crew, often termed a “watch man” to observe the operation of the trash pump and warn the driller if failure occurs, thus allowing the driller to attempt to stop drilling operations in a sufficient amount of time to prevent an overflow condition. Placing a watch man is not desirable because it removes a man from the drilling crew that otherwise could be tending to more critical drilling operations. With the cost of drilling exceeding many thousands of dollars per hour, the loss of time due to the crew being a man short for the purpose of observing the trash pump can add up to substantial costs over the term of the well.
Another measure to prevent fluid spill includes utilizing a second trash pump in the cellar with the thought if one pump fails the other will still operate sufficiently to empty the cellar of collected fluid. However, this method tends to result in one or both of the pumps starving for fluid to pump, which is also used to cool the pump, resulting in premature pump failure from excessive heat.
Yet another measure includes running a pipe in the ground to connect the well cellar to the separate tanks such that the fluid can flow under the force of gravity from the cellar to the tanks However, this method is undesirable due to the considerable costs associated with the installation of the conductor pipe.
Accordingly, there is a need for an improved method and apparatus to observe the fluid level within the well cellar and to alert an operator to the existence of an undesirably high fluid level that indicates trash pump failure.